The present invention relates generally to optical devices and relates more particularly to a birefringent device which provides a birefringent effect without using a birefringent crystal.
Birefringent devices which comprise birefringent crystals are commonly used in optical applications and are well known. For example, birefringent crystals are commonly used in Solc filters for separating multiplexed optical channels in dense wavelength division multiplexing (DWDM) communication systems. Thus, birefringent devices are important device elements in optical signal processing applications and the like.
Birefringent crystals are materials in which the phase velocity of an optical beam propagating therein depends upon the polarization direction of the optical beam. As mentioned above, birefringent devices are important elements in optical signal processing applications and the like. However, birefringent devices which comprise birefringent crystals suffer from inherent limitations which seriously degrade their performance, limit their application and reduce their desirability. Contemporary crystal birefringent devices suffer from limitations imposed by the crystal""s physical, mechanical and optical properties, as well as by problems associated with temperature instability. Further, such contemporary crystal birefringent devices have comparatively small birefringent values. The crystals utilized in such contemporary crystal birefringent devices are comparatively high in cost, both with regard to the synthesis thereof and with regard to their use in fabrication of optical devices, e.g., birefringent devices.
Further, such contemporary crystal birefringent devices have a fixed birefringent value (not taking into consideration undesirable variations due to their temperature instability) and are thus not tunable.
It is desirable to provide a birefringent device which does not utilize a birefringent crystal and thus does not suffer from the inherent shortcomings thereof. More particularly, it is desirable to provide a birefringent device which has comparatively good temperature stability, provides a comparatively wide range of birefringent values, is tunable, and is comparatively less expensive to produce and utilize.
The present invention specifically addresses and alleviates the above-mentioned deficiencies associated with the prior art. More particularly, the present invention comprises a birefringent device comprising a polarization separating device configured to separate a first composite light beam into first and second components thereof. The first and second components are orthogonally polarized with respect to one another. A first path is configured to transmit the first component and has a first optical path length. A second path is configured to transmit the second component and has a second optical path length. The second optical path length is different from the first optical path length. A polarization combining device is configured to recombine the first and second components, so as to form a second composite light beam. The second composite light beam is birefringent with respect to the first composite light beam.
These, as well as other advantages of the present invention, will be more apparent from the following description and drawings. It is understood that changes in the specific structure shown and described may be made within the scope of the claims without departing from the spirit of the invention.